examples of directional hypothesis in psychology

Directional Hypothesis: Definition and 10 Examples

A directional hypothesis refers to a type of hypothesis used in statistical testing that predicts a particular direction of the expected relationship between two variables.

In simpler terms, a directional hypothesis is an educated, specific guess about the direction of an outcome—whether an increase, decrease, or a proclaimed difference in variable sets.

For example, in a study investigating the effects of sleep deprivation on cognitive performance, a directional hypothesis might state that as sleep deprivation (Independent Variable) increases, cognitive performance (Dependent Variable) decreases (Killgore, 2010). Such a hypothesis offers a clear, directional relationship whereby a specific increase or decrease is anticipated.

Global warming provides another notable example of a directional hypothesis. A researcher might hypothesize that as carbon dioxide (CO2) levels increase, global temperatures also increase (Thompson, 2010). In this instance, the hypothesis clearly articulates an upward trend for both variables. 

In any given circumstance, it’s imperative that a directional hypothesis is grounded on solid evidence. For instance, the CO2 and global temperature relationship is based on substantial scientific evidence, and not on a random guess or mere speculation (Florides & Christodoulides, 2009).

Directional vs Non-Directional vs Null Hypotheses

A directional hypothesis is generally contrasted to a non-directional hypothesis. Here’s how they compare:

• Directional hypothesis: A directional hypothesis provides a perspective of the expected relationship between variables, predicting the direction of that relationship (either positive, negative, or a specific difference). 
• Non-directional hypothesis: A non-directional hypothesis denotes the possibility of a relationship between two variables ( the independent and dependent variables ), although this hypothesis does not venture a prediction as to the direction of this relationship (Ali & Bhaskar, 2016). For example, a non-directional hypothesis might state that there exists a relationship between a person’s diet (independent variable) and their mood (dependent variable), without indicating whether improvement in diet enhances mood positively or negatively. Overall, the choice between a directional or non-directional hypothesis depends on the known or anticipated link between the variables under consideration in research studies.

Another very important type of hypothesis that we need to know about is a null hypothesis :

• Null hypothesis : The null hypothesis stands as a universality—the hypothesis that there is no observed effect in the population under study, meaning there is no association between variables (or that the differences are down to chance). For instance, a null hypothesis could be constructed around the idea that changing diet (independent variable) has no discernible effect on a person’s mood (dependent variable) (Yan & Su, 2016). This proposition is the one that we aim to disprove in an experiment.

While directional and non-directional hypotheses involve some integrated expectations about the outcomes (either distinct direction or a vague relationship), a null hypothesis operates on the premise of negating such relationships or effects.

The null hypotheses is typically proposed to be negated or disproved by statistical tests, paving way for the acceptance of an alternate hypothesis (either directional or non-directional).

Directional Hypothesis Examples

1. exercise and heart health.

Research suggests that as regular physical exercise (independent variable) increases, the risk of heart disease (dependent variable) decreases (Jakicic, Davis, Rogers, King, Marcus, Helsel, Rickman, Wahed, Belle, 2016). In this example, a directional hypothesis anticipates that the more individuals maintain routine workouts, the lesser would be their odds of developing heart-related disorders. This assumption is based on the underlying fact that routine exercise can help reduce harmful cholesterol levels, regulate blood pressure, and bring about overall health benefits. Thus, a direction – a decrease in heart disease – is expected in relation with an increase in exercise. 

2. Screen Time and Sleep Quality

Another classic instance of a directional hypothesis can be seen in the relationship between the independent variable, screen time (especially before bed), and the dependent variable, sleep quality. This hypothesis predicts that as screen time before bed increases, sleep quality decreases (Chang, Aeschbach, Duffy, Czeisler, 2015). The reasoning behind this hypothesis is the disruptive effect of artificial light (especially blue light from screens) on melatonin production, a hormone needed to regulate sleep. As individuals spend more time exposed to screens before bed, it is predictably hypothesized that their sleep quality worsens. 

3. Job Satisfaction and Employee Turnover

A typical scenario in organizational behavior research posits that as job satisfaction (independent variable) increases, the rate of employee turnover (dependent variable) decreases (Cheng, Jiang, & Riley, 2017). This directional hypothesis emphasizes that an increased level of job satisfaction would lead to a reduced rate of employees leaving the company. The theoretical basis for this hypothesis is that satisfied employees often tend to be more committed to the organization and are less likely to seek employment elsewhere, thus reducing turnover rates.

4. Healthy Eating and Body Weight

Healthy eating, as the independent variable, is commonly thought to influence body weight, the dependent variable, in a positive way. For example, the hypothesis might state that as consumption of healthy foods increases, an individual’s body weight decreases (Framson, Kristal, Schenk, Littman, Zeliadt, & Benitez, 2009). This projection is based on the premise that healthier foods, such as fruits and vegetables, are generally lower in calories than junk food, assisting in weight management.

5. Sun Exposure and Skin Health

The association between sun exposure (independent variable) and skin health (dependent variable) allows for a definitive hypothesis declaring that as sun exposure increases, the risk of skin damage or skin cancer increases (Whiteman, Whiteman, & Green, 2001). The premise aligns with the understanding that overexposure to the sun’s ultraviolet rays can deteriorate skin health, leading to conditions like sunburn or, in extreme cases, skin cancer.

6. Study Hours and Academic Performance

A regularly assessed relationship in academia suggests that as the number of study hours (independent variable) rises, so too does academic performance (dependent variable) (Nonis, Hudson, Logan, Ford, 2013). The hypothesis proposes a positive correlation , with an increase in study time expected to contribute to enhanced academic outcomes.

7. Screen Time and Eye Strain

It’s commonly hypothesized that as screen time (independent variable) increases, the likelihood of experiencing eye strain (dependent variable) also increases (Sheppard & Wolffsohn, 2018). This is based on the idea that prolonged engagement with digital screens—computers, tablets, or mobile phones—can cause discomfort or fatigue in the eyes, attributing to symptoms of eye strain.

8. Physical Activity and Stress Levels

In the sphere of mental health, it’s often proposed that as physical activity (independent variable) increases, levels of stress (dependent variable) decrease (Stonerock, Hoffman, Smith, Blumenthal, 2015). Regular exercise is known to stimulate the production of endorphins, the body’s natural mood elevators, helping to alleviate stress.

9. Water Consumption and Kidney Health

A common health-related hypothesis might predict that as water consumption (independent variable) increases, the risk of kidney stones (dependent variable) decreases (Curhan, Willett, Knight, & Stampfer, 2004). Here, an increase in water intake is inferred to reduce the risk of kidney stones by diluting the substances that lead to stone formation.

10. Traffic Noise and Sleep Quality

In urban planning research, it’s often supposed that as traffic noise (independent variable) increases, sleep quality (dependent variable) decreases (Muzet, 2007). Increased noise levels, particularly during the night, can result in sleep disruptions, thus, leading to poor sleep quality.

11. Sugar Consumption and Dental Health

In the field of dental health, an example might be stating as one’s sugar consumption (independent variable) increases, dental health (dependent variable) decreases (Sheiham, & James, 2014). This stems from the fact that sugar is a major factor in tooth decay, and increased consumption of sugary foods or drinks leads to a decline in dental health due to the high likelihood of cavities.

See 15 More Examples of Hypotheses Here

A directional hypothesis plays a critical role in research, paving the way for specific predicted outcomes based on the relationship between two variables. These hypotheses clearly illuminate the expected direction—the increase or decrease—of an effect. From predicting the impacts of healthy eating on body weight to forecasting the influence of screen time on sleep quality, directional hypotheses allow for targeted and strategic examination of phenomena. In essence, directional hypotheses provide the crucial path for inquiry, shaping the trajectory of research studies and ultimately aiding in the generation of insightful, relevant findings.

Ali, S., & Bhaskar, S. (2016). Basic statistical tools in research and data analysis. Indian Journal of Anaesthesia, 60 (9), 662-669. doi: https://doi.org/10.4103%2F0019-5049.190623  

Chang, A. M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2015). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proceeding of the National Academy of Sciences, 112 (4), 1232-1237. doi: https://doi.org/10.1073/pnas.1418490112  

Cheng, G. H. L., Jiang, D., & Riley, J. H. (2017). Organizational commitment and intrinsic motivation of regular and contractual primary school teachers in China. New Psychology, 19 (3), 316-326. Doi: https://doi.org/10.4103%2F2249-4863.184631  

Curhan, G. C., Willett, W. C., Knight, E. L., & Stampfer, M. J. (2004). Dietary factors and the risk of incident kidney stones in younger women: Nurses’ Health Study II. Archives of Internal Medicine, 164 (8), 885–891.

Florides, G. A., & Christodoulides, P. (2009). Global warming and carbon dioxide through sciences. Environment international , 35 (2), 390-401. doi: https://doi.org/10.1016/j.envint.2008.07.007

Framson, C., Kristal, A. R., Schenk, J. M., Littman, A. J., Zeliadt, S., & Benitez, D. (2009). Development and validation of the mindful eating questionnaire. Journal of the American Dietetic Association, 109 (8), 1439-1444. doi: https://doi.org/10.1016/j.jada.2009.05.006  

Jakicic, J. M., Davis, K. K., Rogers, R. J., King, W. C., Marcus, M. D., Helsel, D., … & Belle, S. H. (2016). Effect of wearable technology combined with a lifestyle intervention on long-term weight loss: The IDEA randomized clinical trial. JAMA, 316 (11), 1161-1171.

Khan, S., & Iqbal, N. (2013). Study of the relationship between study habits and academic achievement of students: A case of SPSS model. Higher Education Studies, 3 (1), 14-26.

Killgore, W. D. (2010). Effects of sleep deprivation on cognition. Progress in brain research , 185 , 105-129. doi: https://doi.org/10.1016/B978-0-444-53702-7.00007-5  

Marczinski, C. A., & Fillmore, M. T. (2014). Dissociative antagonistic effects of caffeine on alcohol-induced impairment of behavioral control. Experimental and Clinical Psychopharmacology, 22 (4), 298–311. doi: https://psycnet.apa.org/doi/10.1037/1064-1297.11.3.228  

Muzet, A. (2007). Environmental Noise, Sleep and Health. Sleep Medicine Reviews, 11 (2), 135-142. doi: https://doi.org/10.1016/j.smrv.2006.09.001  

Nonis, S. A., Hudson, G. I., Logan, L. B., & Ford, C. W. (2013). Influence of perceived control over time on college students’ stress and stress-related outcomes. Research in Higher Education, 54 (5), 536-552. doi: https://doi.org/10.1023/A:1018753706925  

Sheiham, A., & James, W. P. (2014). A new understanding of the relationship between sugars, dental caries and fluoride use: implications for limits on sugars consumption. Public health nutrition, 17 (10), 2176-2184. Doi: https://doi.org/10.1017/S136898001400113X  

Sheppard, A. L., & Wolffsohn, J. S. (2018). Digital eye strain: prevalence, measurement and amelioration. BMJ open ophthalmology , 3 (1), e000146. doi: http://dx.doi.org/10.1136/bmjophth-2018-000146

Stonerock, G. L., Hoffman, B. M., Smith, P. J., & Blumenthal, J. A. (2015). Exercise as Treatment for Anxiety: Systematic Review and Analysis. Annals of Behavioral Medicine, 49 (4), 542–556. doi: https://doi.org/10.1007/s12160-014-9685-9  

Thompson, L. G. (2010). Climate change: The evidence and our options. The Behavior Analyst , 33 , 153-170. Doi: https://doi.org/10.1007/BF03392211  

Whiteman, D. C., Whiteman, C. A., & Green, A. C. (2001). Childhood sun exposure as a risk factor for melanoma: a systematic review of epidemiologic studies. Cancer Causes & Control, 12 (1), 69-82. doi: https://doi.org/10.1023/A:1008980919928

Yan, X., & Su, X. (2009). Linear regression analysis: theory and computing . New Jersey: World Scientific.

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Statistics Made Easy

What is a Directional Hypothesis? (Definition & Examples)

A statistical hypothesis is an assumption about a population parameter . For example, we may assume that the mean height of a male in the U.S. is 70 inches.

The assumption about the height is the statistical hypothesis and the true mean height of a male in the U.S. is the population parameter .

To test whether a statistical hypothesis about a population parameter is true, we obtain a random sample from the population and perform a hypothesis test on the sample data.

Whenever we perform a hypothesis test, we always write down a null and alternative hypothesis:

• Null Hypothesis (H 0 ): The sample data occurs purely from chance.
• Alternative Hypothesis (H A ): The sample data is influenced by some non-random cause.

A hypothesis test can either contain a directional hypothesis or a non-directional hypothesis:

• Directional hypothesis: The alternative hypothesis contains the less than (“<“) or greater than (“>”) sign. This indicates that we’re testing whether or not there is a positive or negative effect.
• Non-directional hypothesis: The alternative hypothesis contains the not equal (“≠”) sign. This indicates that we’re testing whether or not there is some effect, without specifying the direction of the effect.

Note that directional hypothesis tests are also called “one-tailed” tests and non-directional hypothesis tests are also called “two-tailed” tests.

Check out the following examples to gain a better understanding of directional vs. non-directional hypothesis tests.

Example 1: Baseball Programs

A baseball coach believes a certain 4-week program will increase the mean hitting percentage of his players, which is currently 0.285.

To test this, he measures the hitting percentage of each of his players before and after participating in the program.

He then performs a hypothesis test using the following hypotheses:

• H 0 : μ = .285 (the program will have no effect on the mean hitting percentage)
• H A : μ > .285 (the program will cause mean hitting percentage to increase)

This is an example of a directional hypothesis because the alternative hypothesis contains the greater than “>” sign. The coach believes that the program will influence the mean hitting percentage of his players in a positive direction.

Example 2: Plant Growth

A biologist believes that a certain pesticide will cause plants to grow less during a one-month period than they normally do, which is currently 10 inches.

To test this, she applies the pesticide to each of the plants in her laboratory for one month.

She then performs a hypothesis test using the following hypotheses:

• H 0 : μ = 10 inches (the pesticide will have no effect on the mean plant growth)
• H A : μ < 10 inches (the pesticide will cause mean plant growth to decrease)

This is also an example of a directional hypothesis because the alternative hypothesis contains the less than “<” sign. The biologist believes that the pesticide will influence the mean plant growth in a negative direction.

Example 3: Studying Technique

A professor believes that a certain studying technique will influence the mean score that her students receive on a certain exam, but she’s unsure if it will increase or decrease the mean score, which is currently 82.

To test this, she lets each student use the studying technique for one month leading up to the exam and then administers the same exam to each of the students.

• H 0 : μ = 82 (the studying technique will have no effect on the mean exam score)
• H A : μ ≠ 82 (the studying technique will cause the mean exam score to be different than 82)

This is an example of a non-directional hypothesis because the alternative hypothesis contains the not equal “≠” sign. The professor believes that the studying technique will influence the mean exam score, but doesn’t specify whether it will cause the mean score to increase or decrease.

Additional Resources

Introduction to Hypothesis Testing Introduction to the One Sample t-test Introduction to the Two Sample t-test Introduction to the Paired Samples t-test

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Directional Hypothesis

Definition:

A directional hypothesis is a specific type of hypothesis statement in which the researcher predicts the direction or effect of the relationship between two variables.

Key Features

1. Predicts direction:

Unlike a non-directional hypothesis, which simply states that there is a relationship between two variables, a directional hypothesis specifies the expected direction of the relationship.

2. Involves one-tailed test:

Directional hypotheses typically require a one-tailed statistical test, as they are concerned with whether the relationship is positive or negative, rather than simply whether a relationship exists.

3. Example:

An example of a directional hypothesis would be: “Increasing levels of exercise will result in greater weight loss.”

4. Researcher’s prior belief:

A directional hypothesis is often formed based on the researcher’s prior knowledge, theoretical understanding, or previous empirical evidence relating to the variables under investigation.

5. Confirmatory nature:

Directional hypotheses are considered confirmatory, as they provide a specific prediction that can be tested statistically, allowing researchers to either support or reject the hypothesis.

6. Advantages and disadvantages:

Directional hypotheses help focus the research by explicitly stating the expected relationship, but they can also limit exploration of alternative explanations or unexpected findings.

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Hypotheses; directional and non-directional, what is the difference between an experimental and an alternative hypothesis.

Nothing much! If the study is a laboratory experiment then we can call the hypothesis “an experimental hypothesis”, where we make a prediction about how the IV causes an effect on the DV. If we have a non-experimental design, i.e. we are not able to manipulate the IV as in a natural or quasi-experiment , or if some other research method has been used, then we call it an “alternativehypothesis”, alternative to the null.

Directional hypothesis: A directional (or one tailed hypothesis) states which way you think the results are going to go, for example in an experimental study we might say…”Participants who have been deprived of sleep for 24 hours will have more cold symptoms in the following week after exposure to a virus than participants who have not been sleep deprived”; the hypothesis compares the two groups/conditions and states which one will ….have more/less, be quicker/slower, etc.

If we had a correlational study, the directional hypothesis would state whether we expect a positive or a negative correlation, we are stating how the two variables will be related to each other, e.g. there will be a positive correlation between the number of stressful life events experienced in the last year and the number of coughs and colds suffered, whereby the more life events you have suffered the more coughs and cold you will have had”. The directional hypothesis can also state a negative correlation, e.g. the higher the number of face-book friends, the lower the life satisfaction score “

Non-directional hypothesis: A non-directional (or two tailed hypothesis) simply states that there will be a difference between the two groups/conditions but does not say which will be greater/smaller, quicker/slower etc. Using our example above we would say “There will be a difference between the number of cold symptoms experienced in the following week after exposure to a virus for those participants who have been sleep deprived for 24 hours compared with those who have not been sleep deprived for 24 hours.”

When the study is correlational, we simply state that variables will be correlated but do not state whether the relationship will be positive or negative, e.g. there will be a significant correlation between variable A and variable B.

Null hypothesis The null hypothesis states that the alternative or experimental hypothesis is NOT the case, if your experimental hypothesis was directional you would say…

Participants who have been deprived of sleep for 24 hours will NOT have more cold symptoms in the following week after exposure to a virus than participants who have not been sleep deprived and any difference that does arise will be due to chance alone.

or with a directional correlational hypothesis….

There will NOT be a positive correlation between the number of stress life events experienced in the last year and the number of coughs and colds suffered, whereby the more life events you have suffered the more coughs and cold you will have had”

With a non-directional or  two tailed hypothesis…

There will be NO difference between the number of cold symptoms experienced in the following week after exposure to a virus for those participants who have been sleep deprived for 24 hours compared with those who have not been sleep deprived for 24 hours.

or for a correlational …

there will be NO correlation between variable A and variable B.

When it comes to conducting an inferential stats test, if you have a directional hypothesis , you must do a one tailed test to find out whether your observed value is significant. If you have a non-directional hypothesis , you must do a two tailed test .

Exam Techniques/Advice

• Remember, a decent hypothesis will contain two variables, in the case of an experimental hypothesis there will be an IV and a DV; in a correlational hypothesis there will be two co-variables
• both variables need to be fully operationalised to score the marks, that is you need to be very clear and specific about what you mean by your IV and your DV; if someone wanted to repeat your study, they should be able to look at your hypothesis and know exactly what to change between the two groups/conditions and exactly what to measure (including any units/explanation of rating scales etc, e.g. “where 1 is low and 7 is high”)
• double check the question, did it ask for a directional or non-directional hypothesis?
• if you were asked for a null hypothesis, make sure you always include the phrase “and any difference/correlation (is your study experimental or correlational?) that does arise will be due to chance alone”

Practice Questions:

• Mr Faraz wants to compare the levels of attendance between his psychology group and those of Mr Simon, who teaches a different psychology group. Which of the following is a suitable directional (one tailed) hypothesis for Mr Faraz’s investigation?

A There will be a difference in the levels of attendance between the two psychology groups.

B Students’ level of attendance will be higher in Mr Faraz’s group than Mr Simon’s group.

C Any difference in the levels of attendance between the two psychology groups is due to chance.

D The level of attendance of the students will depend upon who is teaching the groups.

2. Tracy works for the local council. The council is thinking about reducing the number of people it employs to pick up litter from the street. Tracy has been asked to carry out a study to see if having the streets cleaned at less regular intervals will affect the amount of litter the public will drop. She studies a street to compare how much litter is dropped at two different times, once when it has just been cleaned and once after it has not been cleaned for a month.

Write a fully operationalised non-directional (two-tailed) hypothesis for Tracy’s study. (2)

3. Jamila is conducting a practical investigation to look at gender differences in carrying out visuo-spatial tasks. She decides to give males and females a jigsaw puzzle and will time them to see who completes it the fastest. She uses a random sample of pupils from a local school to get her participants.

(a) Write a fully operationalised directional (one tailed) hypothesis for Jamila’s study. (2) (b) Outline one strength and one weakness of the random sampling method. You may refer to Jamila’s use of this type of sampling in your answer. (4)

4. Which of the following is a non-directional (two tailed) hypothesis?

A There is a difference in driving ability with men being better drivers than women

B Women are better at concentrating on more than one thing at a time than men

C Women spend more time doing the cooking and cleaning than men

D There is a difference in the number of men and women who participate in sports

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How to Write a Directional Hypothesis: A Step-by-Step Guide

In research, hypotheses play a crucial role in guiding investigations and making predictions about relationships between variables.

One type of hypothesis that researchers often encounter is the directional hypothesis, also known as a one-tailed hypothesis.

In this blog post, we’ll explore what a directional hypothesis is, why it’s important, and provide a step-by-step guide on how to write one effectively.

Table of Contents

What is a Directional Hypothesis?

A directional hypothesis is a statement that predicts the direction of the relationship between two variables. Unlike non-directional hypotheses, which simply state that there is a relationship between variables without specifying the direction, directional hypotheses make a clear prediction about the expected outcome.

For example, a directional hypothesis might predict that an increase in one variable will lead to a decrease in another.

Examples of Directional Hypotheses

• Increasing the amount of sunlight exposure will lead to higher levels of vitamin D in the body.
• Decreasing the amount of sugar consumption will result in lower body weight among participants.
• Introducing mindfulness meditation techniques will reduce symptoms of anxiety in patients with generalized anxiety disorder.

Why to Write a Directional Hypothesis?

Directional hypotheses offer several advantages in research. They provide researchers with a more focused prediction, allowing them to test specific hypotheses rather than exploring all possible relationships between variables.

This can help streamline research efforts and increase the likelihood of finding meaningful results. Additionally, directional hypotheses are often used in experimental research, where researchers manipulate variables to observe their effects on outcomes.

Step 1: Identify the Variables

Start by identifying the independent variable (the variable you are manipulating) and the dependent variable (the variable you are measuring). Understanding the relationship between these variables is essential for writing a directional hypothesis.

Step 2: Predict the Direction

Based on your understanding of the relationship between the variables, predict the direction of the effect.

Will an increase in the independent variable lead to an increase or decrease in the dependent variable?

Be specific in your prediction.

Step 3: Use Clear Language

Write your directional hypothesis using clear and concise language. Avoid technical jargon or terms that may be difficult for readers to understand. Your hypothesis should be easily understood by both researchers and non-experts.

Step 4: Ensure Testability

Ensure that your hypothesis is testable by collecting data and conducting statistical analysis. You should be able to measure the variables and determine whether the observed results support or refute your hypothesis.

Step 5: Revise and Refine

Review your directional hypothesis to ensure that it accurately reflects your research question and predictions. Make any necessary revisions to improve clarity and specificity.

Writing a directional hypothesis is an essential skill for researchers conducting experiments and investigations.

By following the steps outlined in this guide, you can effectively formulate hypotheses that make clear predictions about the relationship between variables.

Whether you’re a researcher or just starting out in the field, mastering the art of writing directional hypotheses will enhance the quality and rigor of your research endeavors.

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Aims And Hypotheses, Directional And Non-Directional

March 7, 2021 - paper 2 psychology in context | research methods.

• Back to Paper 2 - Research Methods

In Psychology, hypotheses are predictions made by the researcher about the outcome of a study. The research can chose to make a specific prediction about what they feel will happen in their research (a directional hypothesis) or they can make a ‘general,’ ‘less specific’ prediction about the outcome of their research (a non-directional hypothesis). The type of prediction that a researcher makes is usually dependent on whether or not any previous research has also investigated their research aim.

Variables Recap:

The  independent variable  (IV)  is the variable that psychologists  manipulate/change  to see if changing this variable has an effect on the  depen dent variable  (DV).

The  dependent variable (DV)  is the variable that the psychologists  measures  (to see if the IV has had an effect).

It is important that the only variable that is changed in research is the  independent variable (IV),   all other variables have to be kept constant across the control condition and the experimental conditions. Only then will researchers be able to observe the true effects of  just  the independent variable (IV) on the dependent variable (DV).

Research/Experimental Aim(S):

An aim is a clear and precise statement of the purpose of the study. It is a statement of why a research study is taking place. This should include what is being studied and what the study is trying to achieve. (e.g. “This study aims to investigate the effects of alcohol on reaction times”.

It is important that aims created in research are realistic and ethical.

Hypotheses:

This is a testable statement that predicts what the researcher expects to happen in their research. The research study itself is therefore a means of testing whether or not the hypothesis is supported by the findings. If the findings do support the hypothesis then the hypothesis can be retained (i.e., accepted), but if not, then it must be rejected.

Three Different Hypotheses:

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How to Write a Great Hypothesis

Hypothesis Format, Examples, and Tips

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Amy Morin, LCSW, is a psychotherapist and international bestselling author. Her books, including "13 Things Mentally Strong People Don't Do," have been translated into more than 40 languages. Her TEDx talk,  "The Secret of Becoming Mentally Strong," is one of the most viewed talks of all time.

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• The Scientific Method

Hypothesis Format

Falsifiability of a hypothesis, operational definitions, types of hypotheses, hypotheses examples.

• Collecting Data

Frequently Asked Questions

A hypothesis is a tentative statement about the relationship between two or more  variables. It is a specific, testable prediction about what you expect to happen in a study.

One hypothesis example would be a study designed to look at the relationship between sleep deprivation and test performance might have a hypothesis that states: "This study is designed to assess the hypothesis that sleep-deprived people will perform worse on a test than individuals who are not sleep-deprived."

This article explores how a hypothesis is used in psychology research, how to write a good hypothesis, and the different types of hypotheses you might use.

The Hypothesis in the Scientific Method

In the scientific method , whether it involves research in psychology, biology, or some other area, a hypothesis represents what the researchers think will happen in an experiment. The scientific method involves the following steps:

• Forming a question
• Performing background research
• Creating a hypothesis
• Designing an experiment
• Collecting data
• Analyzing the results
• Drawing conclusions
• Communicating the results

The hypothesis is a prediction, but it involves more than a guess. Most of the time, the hypothesis begins with a question which is then explored through background research. It is only at this point that researchers begin to develop a testable hypothesis. Unless you are creating an exploratory study, your hypothesis should always explain what you  expect  to happen.

In a study exploring the effects of a particular drug, the hypothesis might be that researchers expect the drug to have some type of effect on the symptoms of a specific illness. In psychology, the hypothesis might focus on how a certain aspect of the environment might influence a particular behavior.

Remember, a hypothesis does not have to be correct. While the hypothesis predicts what the researchers expect to see, the goal of the research is to determine whether this guess is right or wrong. When conducting an experiment, researchers might explore a number of factors to determine which ones might contribute to the ultimate outcome.

In many cases, researchers may find that the results of an experiment  do not  support the original hypothesis. When writing up these results, the researchers might suggest other options that should be explored in future studies.

In many cases, researchers might draw a hypothesis from a specific theory or build on previous research. For example, prior research has shown that stress can impact the immune system. So a researcher might hypothesize: "People with high-stress levels will be more likely to contract a common cold after being exposed to the virus than people who have low-stress levels."

In other instances, researchers might look at commonly held beliefs or folk wisdom. "Birds of a feather flock together" is one example of folk wisdom that a psychologist might try to investigate. The researcher might pose a specific hypothesis that "People tend to select romantic partners who are similar to them in interests and educational level."

Elements of a Good Hypothesis

So how do you write a good hypothesis? When trying to come up with a hypothesis for your research or experiments, ask yourself the following questions:

• Is your hypothesis based on your research on a topic?
• Can your hypothesis be tested?
• Does your hypothesis include independent and dependent variables?

Before you come up with a specific hypothesis, spend some time doing background research. Once you have completed a literature review, start thinking about potential questions you still have. Pay attention to the discussion section in the  journal articles you read . Many authors will suggest questions that still need to be explored.

To form a hypothesis, you should take these steps:

• Collect as many observations about a topic or problem as you can.
• Evaluate these observations and look for possible causes of the problem.
• Create a list of possible explanations that you might want to explore.
• After you have developed some possible hypotheses, think of ways that you could confirm or disprove each hypothesis through experimentation. This is known as falsifiability.

In the scientific method ,  falsifiability is an important part of any valid hypothesis.   In order to test a claim scientifically, it must be possible that the claim could be proven false.

Students sometimes confuse the idea of falsifiability with the idea that it means that something is false, which is not the case. What falsifiability means is that  if  something was false, then it is possible to demonstrate that it is false.

One of the hallmarks of pseudoscience is that it makes claims that cannot be refuted or proven false.

A variable is a factor or element that can be changed and manipulated in ways that are observable and measurable. However, the researcher must also define how the variable will be manipulated and measured in the study.

For example, a researcher might operationally define the variable " test anxiety " as the results of a self-report measure of anxiety experienced during an exam. A "study habits" variable might be defined by the amount of studying that actually occurs as measured by time.

These precise descriptions are important because many things can be measured in a number of different ways. One of the basic principles of any type of scientific research is that the results must be replicable.   By clearly detailing the specifics of how the variables were measured and manipulated, other researchers can better understand the results and repeat the study if needed.

Some variables are more difficult than others to define. How would you operationally define a variable such as aggression ? For obvious ethical reasons, researchers cannot create a situation in which a person behaves aggressively toward others.

In order to measure this variable, the researcher must devise a measurement that assesses aggressive behavior without harming other people. In this situation, the researcher might utilize a simulated task to measure aggressiveness.

Hypothesis Checklist

• Does your hypothesis focus on something that you can actually test?
• Does your hypothesis include both an independent and dependent variable?
• Can you manipulate the variables?
• Can your hypothesis be tested without violating ethical standards?

The hypothesis you use will depend on what you are investigating and hoping to find. Some of the main types of hypotheses that you might use include:

• Simple hypothesis : This type of hypothesis suggests that there is a relationship between one independent variable and one dependent variable.
• Complex hypothesis : This type of hypothesis suggests a relationship between three or more variables, such as two independent variables and a dependent variable.
• Null hypothesis : This hypothesis suggests no relationship exists between two or more variables.
• Alternative hypothesis : This hypothesis states the opposite of the null hypothesis.
• Statistical hypothesis : This hypothesis uses statistical analysis to evaluate a representative sample of the population and then generalizes the findings to the larger group.
• Logical hypothesis : This hypothesis assumes a relationship between variables without collecting data or evidence.

A hypothesis often follows a basic format of "If {this happens} then {this will happen}." One way to structure your hypothesis is to describe what will happen to the  dependent variable  if you change the  independent variable .

The basic format might be: "If {these changes are made to a certain independent variable}, then we will observe {a change in a specific dependent variable}."

A few examples of simple hypotheses:

• "Students who eat breakfast will perform better on a math exam than students who do not eat breakfast."
• Complex hypothesis: "Students who experience test anxiety before an English exam will get lower scores than students who do not experience test anxiety."​
• "Motorists who talk on the phone while driving will be more likely to make errors on a driving course than those who do not talk on the phone."

Examples of a complex hypothesis include:

• "People with high-sugar diets and sedentary activity levels are more likely to develop depression."
• "Younger people who are regularly exposed to green, outdoor areas have better subjective well-being than older adults who have limited exposure to green spaces."

Examples of a null hypothesis include:

• "Children who receive a new reading intervention will have scores different than students who do not receive the intervention."
• "There will be no difference in scores on a memory recall task between children and adults."

Examples of an alternative hypothesis:

• "Children who receive a new reading intervention will perform better than students who did not receive the intervention."
• "Adults will perform better on a memory task than children." 

Collecting Data on Your Hypothesis

Once a researcher has formed a testable hypothesis, the next step is to select a research design and start collecting data. The research method depends largely on exactly what they are studying. There are two basic types of research methods: descriptive research and experimental research.

Descriptive Research Methods

Descriptive research such as  case studies ,  naturalistic observations , and surveys are often used when it would be impossible or difficult to  conduct an experiment . These methods are best used to describe different aspects of a behavior or psychological phenomenon.

Once a researcher has collected data using descriptive methods, a correlational study can then be used to look at how the variables are related. This type of research method might be used to investigate a hypothesis that is difficult to test experimentally.

Experimental Research Methods

Experimental methods  are used to demonstrate causal relationships between variables. In an experiment, the researcher systematically manipulates a variable of interest (known as the independent variable) and measures the effect on another variable (known as the dependent variable).

Unlike correlational studies, which can only be used to determine if there is a relationship between two variables, experimental methods can be used to determine the actual nature of the relationship—whether changes in one variable actually  cause  another to change.

A Word From Verywell

The hypothesis is a critical part of any scientific exploration. It represents what researchers expect to find in a study or experiment. In situations where the hypothesis is unsupported by the research, the research still has value. Such research helps us better understand how different aspects of the natural world relate to one another. It also helps us develop new hypotheses that can then be tested in the future.

Some examples of how to write a hypothesis include:

• "Staying up late will lead to worse test performance the next day."
• "People who consume one apple each day will visit the doctor fewer times each year."
• "Breaking study sessions up into three 20-minute sessions will lead to better test results than a single 60-minute study session."

The four parts of a hypothesis are:

• The research question
• The independent variable (IV)
• The dependent variable (DV)
• The proposed relationship between the IV and DV

Castillo M. The scientific method: a need for something better? . AJNR Am J Neuroradiol. 2013;34(9):1669-71. doi:10.3174/ajnr.A3401

Nevid J. Psychology: Concepts and Applications. Wadworth, 2013.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Directional Hypothesis Statement

Grasping the intricacies of a directional hypothesis is a stepping stone in advanced research. It offers a clear perspective, pointing towards a specific prediction. From meticulously crafted examples to a thesis statement writing guide, and invaluable tips – this segment shines a light on the essence of formulating a precise and informed directional hypothesis. Embark on this enlightening journey and amplify the quality and clarity of your research endeavors.

What is a Directional hypothesis?

A directional hypothesis, often referred to as a one-tailed hypothesis , is a specific type of hypothesis that predicts the direction of the expected relationship between variables. This type of hypothesis is used when researchers have enough preliminary evidence or theoretical foundation to predict the direction of the relationship, rather than merely stating that a relationship exists.

For example, based on previous studies or established theories, a researcher might hypothesize that a specific intervention will lead to an increase (or decrease) in a certain outcome, rather than just hypothesizing that the intervention will have some effect without specifying the direction of that effect.

What is an example of a Directional hypothesis Statement?

“Children exposed to interactive educational software will demonstrate a higher increase in mathematical skills compared to children who receive traditional classroom instruction.” In this statement, the direction of the expected relationship is clear – the use of interactive educational software is predicted to have a positive effect on mathematical skills.  You may also be interested in our  non directional .

100 Directional Hypothesis Statement Examples

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Directional hypotheses are pivotal in streamlining research focus, providing a clear trajectory by anticipating a specific trend or outcome. They’re an embodiment of informed predictions, crafted based on prior knowledge or insightful observations. Discover below a plethora of examples showcasing the essence of these one-tailed, directional assertions.

• Effect of Diet on Weight: Individuals on a high-fiber diet will lose more weight over a month compared to those on a low-fiber diet.
• Physical Activity and Heart Health: Regular aerobic exercise will lead to a more significant reduction in blood pressure than anaerobic exercise.
• Learning Methods: Students taught via hands-on methods will retain information longer than those taught through lectures.
• Music and Productivity: Employees listening to classical music during work hours will demonstrate higher productivity than those listening to pop music.
• Medication Efficacy: Patients administered Drug X will show faster recovery rates from the flu than those given a placebo.
• Sleep and Memory: Individuals sleeping for 8 hours nightly will have better memory recall than those sleeping only 5 hours.
• Training Intensity and Muscle Growth: Athletes undergoing high-intensity training will exhibit more muscle growth than those in low-intensity programs.
• Organic Foods and Health: Consuming organic foods will lead to lower cholesterol levels compared to consuming non-organic foods.
• Stress and Immunity: Individuals exposed to chronic stress will have a lower immune response than those with minimal stress.
• Digital Learning Platforms: Students utilizing digital learning platforms will score higher in standardized tests than those relying solely on textbooks.
• Caffeine and Alertness: People drinking three cups of coffee daily will show higher alertness levels than non-coffee drinkers.
• Therapy Types: Patients undergoing cognitive-behavioral therapy will show greater reductions in depressive symptoms than those in talk therapy.
• E-Books and Reading Speed: Individuals reading from e-books will process content faster than those reading traditional paper books.
• Urban Living and Mental Health: Residents in urban areas will report higher stress levels than those living in rural regions.
• UV Exposure and Skin Health: Consistent exposure to UV rays will lead to faster skin aging compared to limited sun exposure.
• Yoga and Flexibility: Engaging in daily yoga practices will increase flexibility more significantly than bi-weekly practices.
• Meditation and Stress Reduction: Practicing daily meditation will lead to a more substantial decrease in cortisol levels than sporadic meditation.
• Parenting Styles and Child Independence: Children raised with authoritative parenting styles will demonstrate higher levels of independence than those raised with permissive styles.
• Economic Incentives: Workers receiving performance-based bonuses will exhibit higher job satisfaction than those with fixed salaries.
• Sugar Intake and Energy: Consuming high sugar foods will lead to a more rapid energy decline than low-sugar foods.
• Language Acquisition: Children exposed to bilingual environments before age five will develop superior linguistic skills compared to those exposed later in life.
• Herbal Teas and Sleep: Drinking chamomile tea before bedtime will result in a better sleep quality compared to drinking green tea.
• Posture and Back Pain: Individuals who practice regular posture exercises will experience less chronic back pain than those who don’t.
• Air Quality and Respiratory Issues: Residents in cities with high air pollution will report more respiratory issues than those in cities with cleaner air.
• Online Marketing and Sales: Businesses employing targeted online advertising strategies will see a higher increase in sales than those using traditional advertising methods.
• Pet Ownership and Loneliness: Seniors who own pets will report lower levels of loneliness than those who don’t have pets.
• Dietary Supplements and Immunity: Regular intake of vitamin C supplements will lead to fewer instances of common cold than a placebo.
• Technology and Social Skills: Children who spend over five hours daily on electronic devices will exhibit weaker face-to-face social skills than those who spend less than an hour.
• Remote Work and Productivity: Employees working remotely will report higher job satisfaction than those working in a traditional office setting.
• Organic Farming and Soil Health: Farms employing organic methods will have richer soil nutrient content than those using conventional methods.
• Probiotics and Digestive Health: Consuming probiotics daily will lead to improved gut health compared to not consuming any.
• Art Therapy and Trauma Recovery: Individuals undergoing art therapy will show faster emotional recovery from trauma than those using only talk therapy.
• Video Games and Reflexes: Regular gamers will demonstrate quicker reflex actions than non-gamers.
• Forest Bathing and Stress: Engaging in monthly forest bathing sessions will reduce stress levels more significantly than urban recreational activities.
• Vegan Diet and Heart Health: Individuals following a vegan diet will have a lower risk of heart diseases compared to those on omnivorous diets.
• Mindfulness and Anxiety: Practicing mindfulness meditation will result in a more significant reduction in anxiety levels than general relaxation techniques.
• Solar Energy and Cost Efficiency: Over a decade, households using solar energy will report more cost savings than those relying on traditional electricity sources.
• Active Commuting and Fitness Level: People who cycle or walk to work will have better cardiovascular health than those who commute by car.
• Online Learning and Retention: Students who engage in interactive online learning will retain subject matter better than those using passive video lectures.
• Gardening and Mental Wellbeing: Engaging in regular gardening activities will lead to improved mental well-being compared to non-gardening related hobbies.
• Music Therapy and Memory: Alzheimer’s patients exposed to regular music therapy sessions will display better memory retention than those who aren’t.
• Organic Foods and Allergies: Individuals consuming primarily organic foods will report fewer food allergies compared to those consuming non-organic foods.
• Class Size and Learning Efficiency: Students in smaller class sizes will demonstrate higher academic achievements than those in larger classes.
• Sports and Leadership Skills: Teenagers engaged in team sports will develop stronger leadership skills than those engaged in solitary activities.
• Virtual Reality and Pain Management: Patients using virtual reality as a distraction method during minor surgical procedures will report lower pain levels than those using traditional methods.
• Recycling and Environmental Awareness: Communities with mandatory recycling programs will demonstrate higher environmental awareness than those without such programs.
• Acupuncture and Migraine Relief: Migraine sufferers receiving regular acupuncture treatments will experience fewer episodes than those relying only on medication.
• Urban Green Spaces and Mental Health: Residents in cities with ample green spaces will show lower rates of depression compared to cities predominantly built-up.
• Aquatic Exercises and Joint Health: Individuals with arthritis participating in aquatic exercises will report greater joint mobility than those who do land-based exercises.
• E-books and Reading Comprehension: Students using e-books for study will demonstrate similar reading comprehension levels as those using traditional textbooks.
• Financial Literacy Programs and Debt Management: Adults who attended financial literacy programs in school will manage their debts more effectively than those who didn’t.
• Play-based Learning and Creativity: Children educated through play-based learning methods will exhibit higher creativity levels than those in a strictly academic environment.
• Caffeine Consumption and Cognitive Function: Moderate daily caffeine consumption will lead to improved cognitive function compared to high or no caffeine intake.
• Vegetable Intake and Skin Health: Individuals consuming a diet rich in colorful vegetables will have healthier skin compared to those with minimal vegetable intake.
• Physical Activity and Bone Density: Post-menopausal women engaging in weight-bearing exercises will maintain better bone density than those who don’t.
• Intermittent Fasting and Metabolism: Individuals practicing intermittent fasting will demonstrate a more efficient metabolism rate than those on regular diets.
• Public Transport and Air Quality: Cities with extensive public transport systems will have better air quality than cities primarily reliant on individual car use.
• Sleep Duration and Immunity: Adults sleeping between 7-9 hours nightly will have stronger immune responses than those sleeping less or more than this range.
• Hands-on Learning and Skill Retention: Students taught through hands-on practical methods will retain technical skills better than those taught purely theoretically.
• Nature Exposure and Concentration: Regular breaks involving nature exposure during work will result in higher concentration levels than indoor breaks.
• Yoga and Stress Reduction: Individuals practicing daily yoga sessions will experience a more significant reduction in stress levels compared to non-practitioners.
• Pet Ownership and Loneliness: People who own pets, especially dogs or cats, will report lower feelings of loneliness than those without pets.
• Bilingualism and Cognitive Flexibility: Individuals who are bilingual will exhibit higher cognitive flexibility compared to those who speak only one language.
• Green Tea and Weight Loss: Regular consumption of green tea will result in a higher rate of weight loss than those who consume other beverages.
• Plant-based Diets and Heart Health: Individuals following a plant-based diet will show a reduced risk of cardiovascular diseases compared to those on omnivorous diets.
• Forest Bathing and Mental Wellbeing: People who frequently engage in forest bathing or nature walks will demonstrate improved mental wellbeing than those who don’t.
• Online Learning and Independence: Students who predominantly learn through online platforms will develop stronger independent study habits than those in traditional classroom settings.
• Gardening and Life Satisfaction: Individuals engaged in regular gardening will report higher life satisfaction scores than non-gardeners.
• Video Games and Reflexes: People who play action video games frequently will exhibit quicker reflexes than non-gamers.
• Daily Meditation and Anxiety Levels: Individuals who practice daily meditation sessions will experience reduced anxiety levels compared to those who don’t meditate.
• Volunteering and Self-esteem: Regular volunteers will have higher self-esteem and a more positive outlook than those who don’t volunteer.
• Art Therapy and Emotional Expression: Individuals undergoing art therapy will exhibit a broader range of emotional expression than those undergoing traditional counseling.
• Morning Sunlight and Sleep Patterns: Exposure to morning sunlight will result in better nighttime sleep quality than exposure to late afternoon sunlight.
• Probiotics and Digestive Health: Regular intake of probiotics will lead to improved gut health and fewer digestive issues than those not consuming probiotics.
• Digital Detox and Social Skills: Individuals who frequently engage in digital detoxes will develop better face-to-face social skills than constant device users.
• Physical Libraries and Reading Habits: Students with access to physical libraries will exhibit more consistent reading habits than those relying solely on digital sources.
• Public Speaking Training and Confidence: Individuals who undergo public speaking training will express higher confidence levels in various social scenarios than those who don’t.
• Music Lessons and Mathematical Abilities: Children who take music lessons, especially in instruments like the piano, will show improved mathematical abilities compared to non-musical peers.
• Dance and Coordination: Engaging in dance classes will lead to better physical coordination and balance than other forms of exercise.
• Home Cooking and Nutritional Intake: Individuals who predominantly consume home-cooked meals will have a more balanced nutritional intake than those relying on take-out or restaurant meals.
• Organic Foods and Health Outcomes: Individuals consuming predominantly organic foods will exhibit fewer health issues related to preservatives and pesticides than those consuming conventionally grown foods.
• Podcast Consumption and Listening Skills: People who regularly listen to podcasts will demonstrate better active listening skills compared to those who rarely or never listen to podcasts.
• Urban Farming and Community Engagement: Urban areas with community farming initiatives will experience higher levels of community engagement and social interaction than areas without such initiatives.
• Mindfulness Practices and Emotional Regulation: Individuals practicing mindfulness techniques, like deep breathing or body scans, will manage their emotional responses better than those not practicing mindfulness.
• E-books and Reading Speed: People who primarily read e-books will exhibit a faster reading speed compared to those reading printed books.
• Aerobic Exercises and Endurance: Engaging in regular aerobic exercises will lead to higher endurance levels compared to anaerobic exercises.
• Digital Note-taking and Information Retention: Students who use digital platforms for note-taking will retain and recall information less effectively than those taking handwritten notes.
• Cycling to Work and Cardiovascular Health: Individuals who cycle to work will have better cardiovascular health than those who commute using motorized transportation.
• Active Learning Techniques and Academic Performance: Students exposed to active learning strategies will perform better academically than students in traditional lecture-based settings.
• Ergonomic Workspaces and Physical Discomfort: Workers who use ergonomic office furniture will report fewer musculoskeletal problems than those using conventional office furniture.
• Reforestation Initiatives and Air Quality: Areas with proactive reforestation initiatives will have significantly better air quality than areas without such efforts.
• Mediterranean Diet and Lifespan: People following a Mediterranean diet will generally have a longer lifespan compared to those following Western diets.
• Virtual Reality Training and Skill Acquisition: Individuals trained using virtual reality platforms will acquire new skills more rapidly than those trained using traditional methods.
• Solar Energy Adoption and Electricity Bills: Households that adopt solar energy solutions will experience lower monthly electricity bills than those relying solely on grid electricity.
• Journaling and Stress Reduction: Regular journaling will lead to a more significant reduction in perceived stress levels than non-journaling practices.
• Noise-cancelling Headphones and Productivity: Workers using noise-cancelling headphones in open office environments will show higher productivity levels than those not using such headphones.
• Early Birds and Task Efficiency: Individuals who start their day early, or “early birds”, will generally be more efficient in completing tasks than night owls.
• Coding Bootcamps and Job Placement: Graduates from coding bootcamps will find job placements more rapidly than those with only traditional computer science degrees.
• Plant-based Milks and Lactose Intolerance: Consuming plant-based milks, such as almond or oat milk, will cause fewer digestive problems for lactose-intolerant individuals than cow’s milk.
• Sensory Deprivation Tanks and Creativity: Regular sessions in sensory deprivation tanks will lead to heightened creativity levels compared to traditional relaxation methods.

Directional Hypothesis Statement Examples for Psychology

In the realm of psychology, directional psychology hypothesis are valuable as they specifically predict the nature and direction of a relationship or effect. These statements make pointed predictions about expected outcomes in psychological studies, paving the way for focused investigations.

• Emotion Regulation Techniques: Individuals trained in emotion regulation techniques will exhibit lower levels of anxiety than those untrained.
• Positive Reinforcement in Learning: Children exposed to positive reinforcement will exhibit faster learning rates than those exposed to negative reinforcement.
• Cognitive Behavioral Therapy and Depression: Patients undergoing cognitive-behavioral therapy will show more significant improvements in depressive symptoms than those using other therapeutic methods.
• Social Media Use and Self-esteem: Adolescents with higher social media usage will report lower self-esteem than their less active counterparts.
• Mindfulness Meditation and Attention Span: Regular practitioners of mindfulness meditation will have longer attention spans than non-practitioners.
• Childhood Trauma and Adult Relationships: Individuals who experienced trauma in childhood will display more attachment issues in adult romantic relationships than those without such experiences.
• Group Therapy and Social Skills: Individuals attending group therapy will demonstrate improved social skills compared to those receiving individual therapy.
• Extrinsic Motivation and Task Performance: Students driven by extrinsic motivation will have lower task persistence than those driven by intrinsic motivation.
• Visual Imagery and Memory Retention: Participants using visual imagery techniques will recall lists of items more effectively than those using rote memorization.
• Parenting Styles and Adolescent Rebellion: Adolescents raised with authoritarian parenting styles will show higher levels of rebellion than those raised with permissive styles.

Directional Hypothesis Statement Examples for Research

In research, a directional research hypothesis narrows down the prediction to a specific direction of the effect. These hypotheses can serve various fields, guiding researchers toward certain anticipated outcomes, making the study’s goal clearer.

• Online Learning Platforms and Student Engagement: Students using interactive online learning platforms will have higher engagement levels than those using traditional online formats.
• Work from Home and Employee Productivity: Employees working from home will report higher job satisfaction but slightly reduced productivity compared to office-going employees.
• Green Spaces and Urban Well-being: Urban areas with more green spaces will have residents reporting higher well-being scores than areas dominated by concrete.
• Dietary Fiber Intake and Digestive Health: Individuals consuming diets rich in fiber will have fewer digestive issues than those on low-fiber diets.
• Public Transportation and Air Quality: Cities that invest more in public transportation will experience better air quality than cities reliant on individual car usage.
• Gamification and Learning Outcomes: Educational modules that incorporate gamification will yield better learning outcomes than traditional modules.
• Open Source Software and System Security: Systems using open-source software will encounter fewer security breaches than those using proprietary software.
• Organic Farming and Soil Health: Farmlands practicing organic farming methods will have richer soil quality than conventionally farmed lands.
• Renewable Energy Sources and Power Grid Stability: Power grids utilizing a higher percentage of renewable energy sources will experience fewer outages than those predominantly using fossil fuels.
• Artificial Sweeteners and Weight Gain: Regular consumers of artificial sweeteners will not necessarily exhibit lower weight gain compared to consumers of natural sugars.

Directional Hypothesis Statement Examples for Correlation Study

Correlation studies evaluate the relationship between two or more variables. Directional hypotheses in correlation studies anticipate a specific type of association – either positive, negative, or neutral.

• Physical Activity and Mental Health: There will be a positive correlation between regular physical activity levels and self-reported mental well-being.
• Sedentary Lifestyle and Cardiovascular Issues: An increased sedentary lifestyle duration will correlate positively with cardiovascular health issues.
• Reading Habits and Vocabulary Size: There will be a positive correlation between the frequency of reading and the breadth of an individual’s vocabulary.
• Fast Food Consumption and Health Risks: A higher frequency of fast food consumption will correlate with increased health risks, such as obesity or high blood pressure.
• Financial Literacy and Debt Management: Individuals with higher financial literacy will have a negative correlation with unmanaged debts.
• Sleep Duration and Cognitive Performance: There will be a positive correlation between the optimal sleep duration (7-9 hours) and cognitive performance in adults.
• Volunteering and Life Satisfaction: Individuals who volunteer regularly will show a positive correlation with overall life satisfaction scores.
• Alcohol Consumption and Reaction Time: A higher frequency and quantity of alcohol consumption will negatively correlate with reaction times in motor tasks.
• Class Attendance and Academic Grades: There will be a positive correlation between the number of classes attended and the final academic grades of students.
• Eco-friendly Practices and Brand Loyalty: Brands adopting more eco-friendly practices will experience a positive correlation with consumer loyalty and trust.

Directional Hypothesis vs Non-Directional Hypothesis

Directional Hypothesis: A directional hypothesis , as the name implies, provides a specific direction for the expected relationship or difference between variables. It predicts which group will have higher or lower scores or how two variables will relate specifically, such as predicting that one variable will increase as the other decreases.

Advantages of a Directional Hypothesis:

• Offers clarity in predictions.
• Simplifies data interpretation, since the expected outcome is clearly stated.
• Can be based on previous research or established theories, lending more weight to its predictions.

Example of Directional Hypothesis: “Students who receive mindfulness training will have lower stress levels than those who do not receive such training.”

Non-Directional Hypothesis (Two-tailed Hypothesis): A non-directional hypothesis , on the other hand, merely states that there will be a difference between the two groups or a relationship between two variables without specifying the nature of this difference or relationship.

Advantages of a Non-Directional Hypothesis:

• Useful when research is exploratory in nature.
• Provides a broader scope for exploring unexpected results.
• Less bias as it doesn’t anticipate a specific outcome.

Example of Non-Directional Hypothesis: “Students who receive mindfulness training will have different stress levels than those who do not receive such training.”

How do you write a Directional Hypothesis Statement? – Step by Step Guide

1. Identify Your Variables: Before drafting a hypothesis, understand the dependent and independent variables in your study.

2. Review Previous Research: Consider findings from past studies or established theories to make informed predictions.

3. Be Specific: Clearly state which group or condition you expect to have higher or lower scores or how the variables will relate.

4. Keep It Simple: Ensure that the hypothesis is concise and free of jargon.

5. Make It Testable: Your hypothesis should be framed in such a way that it can be empirically tested through experiments or observations.

6. Revise and Refine: After drafting your hypothesis, review it to ensure clarity and relevance. Get feedback if possible.

7. State Confidently: Use definitive language, such as “will” rather than “might.”

Example of Writing Directional Hypothesis: Based on a study that indicates mindfulness reduces stress, and intending to research its impact on students, you might draft: “Students undergoing mindfulness practices will report lower stress levels.”

Tips for Writing a Directional Hypothesis Statement

1. Base Your Predictions on Evidence: Whenever possible, root your hypotheses in existing literature or preliminary observations.

2. Avoid Ambiguity: Be clear about the specific groups or conditions you are comparing.

3. Stay Focused: A hypothesis should address one primary question or relationship. If you find your hypothesis complicated, consider breaking it into multiple hypotheses.

4. Use Simple Language: Complex wording can muddle the clarity of your hypothesis. Ensure it’s understandable, even to those outside your field.

5. Review and Refine: After drafting, set it aside, then revisit with fresh eyes. It can also be helpful to get peers or mentors to review your hypothesis.

6. Avoid Personal Bias: Ensure your hypothesis is based on empirical evidence or theories and not personal beliefs or biases.

Remember, a directional hypothesis is just a starting point. While it provides a roadmap for your research, it’s essential to remain open to whatever results your study yields, even if they contradict your initial predictions.

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Home » What is a Hypothesis – Types, Examples and Writing Guide

What is a Hypothesis – Types, Examples and Writing Guide

Table of Contents

Definition:

Hypothesis is an educated guess or proposed explanation for a phenomenon, based on some initial observations or data. It is a tentative statement that can be tested and potentially proven or disproven through further investigation and experimentation.

Hypothesis is often used in scientific research to guide the design of experiments and the collection and analysis of data. It is an essential element of the scientific method, as it allows researchers to make predictions about the outcome of their experiments and to test those predictions to determine their accuracy.

Types of Hypothesis

Types of Hypothesis are as follows:

Research Hypothesis

A research hypothesis is a statement that predicts a relationship between variables. It is usually formulated as a specific statement that can be tested through research, and it is often used in scientific research to guide the design of experiments.

Null Hypothesis

The null hypothesis is a statement that assumes there is no significant difference or relationship between variables. It is often used as a starting point for testing the research hypothesis, and if the results of the study reject the null hypothesis, it suggests that there is a significant difference or relationship between variables.

Alternative Hypothesis

An alternative hypothesis is a statement that assumes there is a significant difference or relationship between variables. It is often used as an alternative to the null hypothesis and is tested against the null hypothesis to determine which statement is more accurate.

Directional Hypothesis

A directional hypothesis is a statement that predicts the direction of the relationship between variables. For example, a researcher might predict that increasing the amount of exercise will result in a decrease in body weight.

Non-directional Hypothesis

A non-directional hypothesis is a statement that predicts the relationship between variables but does not specify the direction. For example, a researcher might predict that there is a relationship between the amount of exercise and body weight, but they do not specify whether increasing or decreasing exercise will affect body weight.

Statistical Hypothesis

A statistical hypothesis is a statement that assumes a particular statistical model or distribution for the data. It is often used in statistical analysis to test the significance of a particular result.

Composite Hypothesis

A composite hypothesis is a statement that assumes more than one condition or outcome. It can be divided into several sub-hypotheses, each of which represents a different possible outcome.

Empirical Hypothesis

An empirical hypothesis is a statement that is based on observed phenomena or data. It is often used in scientific research to develop theories or models that explain the observed phenomena.

Simple Hypothesis

A simple hypothesis is a statement that assumes only one outcome or condition. It is often used in scientific research to test a single variable or factor.

Complex Hypothesis

A complex hypothesis is a statement that assumes multiple outcomes or conditions. It is often used in scientific research to test the effects of multiple variables or factors on a particular outcome.

Applications of Hypothesis

Hypotheses are used in various fields to guide research and make predictions about the outcomes of experiments or observations. Here are some examples of how hypotheses are applied in different fields:

• Science : In scientific research, hypotheses are used to test the validity of theories and models that explain natural phenomena. For example, a hypothesis might be formulated to test the effects of a particular variable on a natural system, such as the effects of climate change on an ecosystem.
• Medicine : In medical research, hypotheses are used to test the effectiveness of treatments and therapies for specific conditions. For example, a hypothesis might be formulated to test the effects of a new drug on a particular disease.
• Psychology : In psychology, hypotheses are used to test theories and models of human behavior and cognition. For example, a hypothesis might be formulated to test the effects of a particular stimulus on the brain or behavior.
• Sociology : In sociology, hypotheses are used to test theories and models of social phenomena, such as the effects of social structures or institutions on human behavior. For example, a hypothesis might be formulated to test the effects of income inequality on crime rates.
• Business : In business research, hypotheses are used to test the validity of theories and models that explain business phenomena, such as consumer behavior or market trends. For example, a hypothesis might be formulated to test the effects of a new marketing campaign on consumer buying behavior.
• Engineering : In engineering, hypotheses are used to test the effectiveness of new technologies or designs. For example, a hypothesis might be formulated to test the efficiency of a new solar panel design.

How to write a Hypothesis

Here are the steps to follow when writing a hypothesis:

Identify the Research Question

The first step is to identify the research question that you want to answer through your study. This question should be clear, specific, and focused. It should be something that can be investigated empirically and that has some relevance or significance in the field.

Conduct a Literature Review

Before writing your hypothesis, it’s essential to conduct a thorough literature review to understand what is already known about the topic. This will help you to identify the research gap and formulate a hypothesis that builds on existing knowledge.

Determine the Variables

The next step is to identify the variables involved in the research question. A variable is any characteristic or factor that can vary or change. There are two types of variables: independent and dependent. The independent variable is the one that is manipulated or changed by the researcher, while the dependent variable is the one that is measured or observed as a result of the independent variable.

Formulate the Hypothesis

Based on the research question and the variables involved, you can now formulate your hypothesis. A hypothesis should be a clear and concise statement that predicts the relationship between the variables. It should be testable through empirical research and based on existing theory or evidence.

Write the Null Hypothesis

The null hypothesis is the opposite of the alternative hypothesis, which is the hypothesis that you are testing. The null hypothesis states that there is no significant difference or relationship between the variables. It is important to write the null hypothesis because it allows you to compare your results with what would be expected by chance.

Refine the Hypothesis

After formulating the hypothesis, it’s important to refine it and make it more precise. This may involve clarifying the variables, specifying the direction of the relationship, or making the hypothesis more testable.

Examples of Hypothesis

Here are a few examples of hypotheses in different fields:

• Psychology : “Increased exposure to violent video games leads to increased aggressive behavior in adolescents.”
• Biology : “Higher levels of carbon dioxide in the atmosphere will lead to increased plant growth.”
• Sociology : “Individuals who grow up in households with higher socioeconomic status will have higher levels of education and income as adults.”
• Education : “Implementing a new teaching method will result in higher student achievement scores.”
• Marketing : “Customers who receive a personalized email will be more likely to make a purchase than those who receive a generic email.”
• Physics : “An increase in temperature will cause an increase in the volume of a gas, assuming all other variables remain constant.”
• Medicine : “Consuming a diet high in saturated fats will increase the risk of developing heart disease.”

Purpose of Hypothesis

The purpose of a hypothesis is to provide a testable explanation for an observed phenomenon or a prediction of a future outcome based on existing knowledge or theories. A hypothesis is an essential part of the scientific method and helps to guide the research process by providing a clear focus for investigation. It enables scientists to design experiments or studies to gather evidence and data that can support or refute the proposed explanation or prediction.

The formulation of a hypothesis is based on existing knowledge, observations, and theories, and it should be specific, testable, and falsifiable. A specific hypothesis helps to define the research question, which is important in the research process as it guides the selection of an appropriate research design and methodology. Testability of the hypothesis means that it can be proven or disproven through empirical data collection and analysis. Falsifiability means that the hypothesis should be formulated in such a way that it can be proven wrong if it is incorrect.

In addition to guiding the research process, the testing of hypotheses can lead to new discoveries and advancements in scientific knowledge. When a hypothesis is supported by the data, it can be used to develop new theories or models to explain the observed phenomenon. When a hypothesis is not supported by the data, it can help to refine existing theories or prompt the development of new hypotheses to explain the phenomenon.

When to use Hypothesis

Here are some common situations in which hypotheses are used:

• In scientific research , hypotheses are used to guide the design of experiments and to help researchers make predictions about the outcomes of those experiments.
• In social science research , hypotheses are used to test theories about human behavior, social relationships, and other phenomena.
• I n business , hypotheses can be used to guide decisions about marketing, product development, and other areas. For example, a hypothesis might be that a new product will sell well in a particular market, and this hypothesis can be tested through market research.

Characteristics of Hypothesis

Here are some common characteristics of a hypothesis:

• Testable : A hypothesis must be able to be tested through observation or experimentation. This means that it must be possible to collect data that will either support or refute the hypothesis.
• Falsifiable : A hypothesis must be able to be proven false if it is not supported by the data. If a hypothesis cannot be falsified, then it is not a scientific hypothesis.
• Clear and concise : A hypothesis should be stated in a clear and concise manner so that it can be easily understood and tested.
• Based on existing knowledge : A hypothesis should be based on existing knowledge and research in the field. It should not be based on personal beliefs or opinions.
• Specific : A hypothesis should be specific in terms of the variables being tested and the predicted outcome. This will help to ensure that the research is focused and well-designed.
• Tentative: A hypothesis is a tentative statement or assumption that requires further testing and evidence to be confirmed or refuted. It is not a final conclusion or assertion.
• Relevant : A hypothesis should be relevant to the research question or problem being studied. It should address a gap in knowledge or provide a new perspective on the issue.

Advantages of Hypothesis

Hypotheses have several advantages in scientific research and experimentation:

• Guides research: A hypothesis provides a clear and specific direction for research. It helps to focus the research question, select appropriate methods and variables, and interpret the results.
• Predictive powe r: A hypothesis makes predictions about the outcome of research, which can be tested through experimentation. This allows researchers to evaluate the validity of the hypothesis and make new discoveries.
• Facilitates communication: A hypothesis provides a common language and framework for scientists to communicate with one another about their research. This helps to facilitate the exchange of ideas and promotes collaboration.
• Efficient use of resources: A hypothesis helps researchers to use their time, resources, and funding efficiently by directing them towards specific research questions and methods that are most likely to yield results.
• Provides a basis for further research: A hypothesis that is supported by data provides a basis for further research and exploration. It can lead to new hypotheses, theories, and discoveries.
• Increases objectivity: A hypothesis can help to increase objectivity in research by providing a clear and specific framework for testing and interpreting results. This can reduce bias and increase the reliability of research findings.

Limitations of Hypothesis

Some Limitations of the Hypothesis are as follows:

• Limited to observable phenomena: Hypotheses are limited to observable phenomena and cannot account for unobservable or intangible factors. This means that some research questions may not be amenable to hypothesis testing.
• May be inaccurate or incomplete: Hypotheses are based on existing knowledge and research, which may be incomplete or inaccurate. This can lead to flawed hypotheses and erroneous conclusions.
• May be biased: Hypotheses may be biased by the researcher’s own beliefs, values, or assumptions. This can lead to selective interpretation of data and a lack of objectivity in research.
• Cannot prove causation: A hypothesis can only show a correlation between variables, but it cannot prove causation. This requires further experimentation and analysis.
• Limited to specific contexts: Hypotheses are limited to specific contexts and may not be generalizable to other situations or populations. This means that results may not be applicable in other contexts or may require further testing.
• May be affected by chance : Hypotheses may be affected by chance or random variation, which can obscure or distort the true relationship between variables.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

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On This Page:

A null hypothesis is a statistical concept suggesting no significant difference or relationship between measured variables. It’s the default assumption unless empirical evidence proves otherwise.

The null hypothesis states no relationship exists between the two variables being studied (i.e., one variable does not affect the other).

The null hypothesis is the statement that a researcher or an investigator wants to disprove.

Testing the null hypothesis can tell you whether your results are due to the effects of manipulating ​ the dependent variable or due to random chance. 

How to Write a Null Hypothesis

Null hypotheses (H0) start as research questions that the investigator rephrases as statements indicating no effect or relationship between the independent and dependent variables.

It is a default position that your research aims to challenge or confirm.

For example, if studying the impact of exercise on weight loss, your null hypothesis might be:

There is no significant difference in weight loss between individuals who exercise daily and those who do not.

Examples of Null Hypotheses

When do we reject the null hypothesis .

We reject the null hypothesis when the data provide strong enough evidence to conclude that it is likely incorrect. This often occurs when the p-value (probability of observing the data given the null hypothesis is true) is below a predetermined significance level.

If the collected data does not meet the expectation of the null hypothesis, a researcher can conclude that the data lacks sufficient evidence to back up the null hypothesis, and thus the null hypothesis is rejected. 

Rejecting the null hypothesis means that a relationship does exist between a set of variables and the effect is statistically significant ( p > 0.05).

If the data collected from the random sample is not statistically significance , then the null hypothesis will be accepted, and the researchers can conclude that there is no relationship between the variables. 

You need to perform a statistical test on your data in order to evaluate how consistent it is with the null hypothesis. A p-value is one statistical measurement used to validate a hypothesis against observed data.

Calculating the p-value is a critical part of null-hypothesis significance testing because it quantifies how strongly the sample data contradicts the null hypothesis.

The level of statistical significance is often expressed as a  p  -value between 0 and 1. The smaller the p-value, the stronger the evidence that you should reject the null hypothesis.

Usually, a researcher uses a confidence level of 95% or 99% (p-value of 0.05 or 0.01) as general guidelines to decide if you should reject or keep the null.

When your p-value is less than or equal to your significance level, you reject the null hypothesis.

In other words, smaller p-values are taken as stronger evidence against the null hypothesis. Conversely, when the p-value is greater than your significance level, you fail to reject the null hypothesis.

In this case, the sample data provides insufficient data to conclude that the effect exists in the population.

Because you can never know with complete certainty whether there is an effect in the population, your inferences about a population will sometimes be incorrect.

When you incorrectly reject the null hypothesis, it’s called a type I error. When you incorrectly fail to reject it, it’s called a type II error.

Why Do We Never Accept The Null Hypothesis?

The reason we do not say “accept the null” is because we are always assuming the null hypothesis is true and then conducting a study to see if there is evidence against it. And, even if we don’t find evidence against it, a null hypothesis is not accepted.

A lack of evidence only means that you haven’t proven that something exists. It does not prove that something doesn’t exist. 

It is risky to conclude that the null hypothesis is true merely because we did not find evidence to reject it. It is always possible that researchers elsewhere have disproved the null hypothesis, so we cannot accept it as true, but instead, we state that we failed to reject the null. 

One can either reject the null hypothesis, or fail to reject it, but can never accept it.

Why Do We Use The Null Hypothesis?

We can never prove with 100% certainty that a hypothesis is true; We can only collect evidence that supports a theory. However, testing a hypothesis can set the stage for rejecting or accepting this hypothesis within a certain confidence level.

The null hypothesis is useful because it can tell us whether the results of our study are due to random chance or the manipulation of a variable (with a certain level of confidence).

A null hypothesis is rejected if the measured data is significantly unlikely to have occurred and a null hypothesis is accepted if the observed outcome is consistent with the position held by the null hypothesis.

Rejecting the null hypothesis sets the stage for further experimentation to see if a relationship between two variables exists. 

Hypothesis testing is a critical part of the scientific method as it helps decide whether the results of a research study support a particular theory about a given population. Hypothesis testing is a systematic way of backing up researchers’ predictions with statistical analysis.

It helps provide sufficient statistical evidence that either favors or rejects a certain hypothesis about the population parameter. 

Purpose of a Null Hypothesis 

• The primary purpose of the null hypothesis is to disprove an assumption. 
• Whether rejected or accepted, the null hypothesis can help further progress a theory in many scientific cases.
• A null hypothesis can be used to ascertain how consistent the outcomes of multiple studies are.

Do you always need both a Null Hypothesis and an Alternative Hypothesis?

The null (H0) and alternative (Ha or H1) hypotheses are two competing claims that describe the effect of the independent variable on the dependent variable. They are mutually exclusive, which means that only one of the two hypotheses can be true. 

While the null hypothesis states that there is no effect in the population, an alternative hypothesis states that there is statistical significance between two variables. 

The goal of hypothesis testing is to make inferences about a population based on a sample. In order to undertake hypothesis testing, you must express your research hypothesis as a null and alternative hypothesis. Both hypotheses are required to cover every possible outcome of the study. 

What is the difference between a null hypothesis and an alternative hypothesis?

The alternative hypothesis is the complement to the null hypothesis. The null hypothesis states that there is no effect or no relationship between variables, while the alternative hypothesis claims that there is an effect or relationship in the population.

It is the claim that you expect or hope will be true. The null hypothesis and the alternative hypothesis are always mutually exclusive, meaning that only one can be true at a time.

What are some problems with the null hypothesis?

One major problem with the null hypothesis is that researchers typically will assume that accepting the null is a failure of the experiment. However, accepting or rejecting any hypothesis is a positive result. Even if the null is not refuted, the researchers will still learn something new.

Why can a null hypothesis not be accepted?

We can either reject or fail to reject a null hypothesis, but never accept it. If your test fails to detect an effect, this is not proof that the effect doesn’t exist. It just means that your sample did not have enough evidence to conclude that it exists.

We can’t accept a null hypothesis because a lack of evidence does not prove something that does not exist. Instead, we fail to reject it.

Failing to reject the null indicates that the sample did not provide sufficient enough evidence to conclude that an effect exists.

If the p-value is greater than the significance level, then you fail to reject the null hypothesis.

Is a null hypothesis directional or non-directional?

A hypothesis test can either contain an alternative directional hypothesis or a non-directional alternative hypothesis. A directional hypothesis is one that contains the less than (“<“) or greater than (“>”) sign.

A nondirectional hypothesis contains the not equal sign (“≠”).  However, a null hypothesis is neither directional nor non-directional.

A null hypothesis is a prediction that there will be no change, relationship, or difference between two variables.

The directional hypothesis or nondirectional hypothesis would then be considered alternative hypotheses to the null hypothesis.

Gill, J. (1999). The insignificance of null hypothesis significance testing.  Political research quarterly ,  52 (3), 647-674.

Krueger, J. (2001). Null hypothesis significance testing: On the survival of a flawed method.  American Psychologist ,  56 (1), 16.

Masson, M. E. (2011). A tutorial on a practical Bayesian alternative to null-hypothesis significance testing.  Behavior research methods ,  43 , 679-690.

Nickerson, R. S. (2000). Null hypothesis significance testing: a review of an old and continuing controversy.  Psychological methods ,  5 (2), 241.

Rozeboom, W. W. (1960). The fallacy of the null-hypothesis significance test.  Psychological bulletin ,  57 (5), 416.

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Non-Directional Hypothesis

A non-directional hypothesis is a two-tailed hypothesis that does not predict the direction of the difference or relationship (e.g. girls and boys are different in terms of helpfulness).

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